Re: [PATCH v2 1/3] xen/privcmd: Corrected error handling path
From: JÃrgen GroÃ
Date: Tue Jul 07 2020 - 07:45:46 EST
On 07.07.20 13:40, Souptick Joarder wrote:
On Tue, Jul 7, 2020 at 3:05 PM JÃrgen Groà <jgross@xxxxxxxx> wrote:
On 06.07.20 20:16, Souptick Joarder wrote:
Previously, if lock_pages() end up partially mapping pages, it used
to return -ERRNO due to which unlock_pages() have to go through
each pages[i] till *nr_pages* to validate them. This can be avoided
by passing correct number of partially mapped pages & -ERRNO separately,
while returning from lock_pages() due to error.
With this fix unlock_pages() doesn't need to validate pages[i] till
*nr_pages* for error scenario and few condition checks can be ignored.
Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Paul Durrant <xadimgnik@xxxxxxxxx>
---
drivers/xen/privcmd.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index a250d11..33677ea 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -580,13 +580,13 @@ static long privcmd_ioctl_mmap_batch(
static int lock_pages(
struct privcmd_dm_op_buf kbufs[], unsigned int num,
- struct page *pages[], unsigned int nr_pages)
+ struct page *pages[], unsigned int nr_pages, unsigned int *pinned)
{
unsigned int i;
+ int page_count = 0;
Initial value shouldn't be needed, and ...
for (i = 0; i < num; i++) {
unsigned int requested;
- int pinned;
... you could move the declaration here.
With that done you can add my
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Ok. But does it going make any difference other than limiting scope ?
Dropping the initializer surely does, and in the end page_count just
replaces the former pinned variable, so why would we want to widen the
scope with this patch?
Juergen